I have only one testicle and this has been a chastity problem up until now. The HoD600S is perfect and just what I've been looking for, for a long time. I have used the smallest ring and a fairly short spacer, it is so comfortable to wear, I don't think it would be any good for use as a punishment tool, ha, ha! My tiny penis is hardly noticeable in the cage so I'm off to watch some "FemDom" videos to force it to get hard.
After a while my tiny penis tried to escape and so I have removed the spacer completely and used a shorter pin, it's fine now-no escape for me tonight.